Let $G=PSU_3(q)$ and $q=p^n$, where $n$ is odd. Can we conclude that $PSU_3(p)$ is a subgroup of $G$?
1 Answer
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Yes, because $SU_3(q) \subset SU_3(q^2)$ is the subgroup of elements Galois-conjugate to their inverse. $SU_3(p)$ is the subgroup of elements defined over $p$ and Galois-conjugate to their inverse. Since the relevant Galois action is the same, they are the same. Then we mod out by the centers, which preserves inclusions.